Transponder bolt seal and a housing for a transponder

This invention relates to electronic security seals. It also relates to housings for transponders. In particular, but not exclusively, the present invention relates to electronic security seals for use on shipping containers.

The security of containers has become an important issue in today\'s security-conscious environment. This is particularly apparent in the shipping of containers across borders. The locking of loaded containers to prevent unauthorised access after the containers have been loaded and before the containers reach their destination is now seen as an important, if not mandatory security precaution.

Of course, a lock on a container may be removed and then replaced. Therefore, it is important that tampering with a lock is able to be detected. To assist with the identification of tampering with locks, electronic seals have been utilised.

One form of electronic seal that has been used in the past is an electronic tagging device that wirelessly transmits information to an interrogator. This information identifies whether the lock has been tampered with.

U.S. Pat. No. 6,265,973 (Brammall et al.) describes an electronic security seal. A conductor along the bolt shank is connected to a circuit and provides a tamper evident signal to the circuit when the bolt is severed. The circuit senses removal of the bolt or severed bolt condition and generates a “tamper” signal, which is transmitted to a local receiver/reader.

U.S. Pat. No. 6,747,558 (Thorne et al.) describes a method and apparatus for providing container security with a tag. A device includes a bolt, which extends through openings in a latch mechanism on the container. The bolt also passes through spaced coils of the seal device. The sealed device uses one coil to generate a magnetic field, while monitoring the corresponding magnetic field induced in the other coil. Tampering with the bolt affects the magnetic field, which in turn permits the seal device to detect the tampering. The seal device periodically transmits wireless signals, which can be remotely received for the purpose of tracking the container and monitoring the integrity of the seal.

A major disadvantage of providing sophisticated electronic security seals is the increased cost involved in shipping containers. Even if the devices are made to be reusable, there is the associated cost, inconvenience and possible additional security issues related to the reuse of electronic seals. In addition, electronic seals that actively transmit signals may be subject to stringent regulations regarding the maximum power of transmission and the frequency bands in which transmissions may be made. These regulations may change from jurisdiction to jurisdiction and over time. There is also the problem of passive transponders interfering with the signals from other passive transponders when interrogated. This problem remains even in applications where evidence of tampering with a lock is not required.

Apart from the sealing function of electronic seals, there are many other applications where removal or tampering with a value item needs to be detected.

It is therefore an object the present invention to overcome or ameliorate problems with electronic seals and/or transponder devices at present, or at least to provide the public with a useful alternative.

Any reference in this specification to the prior art does not constitute, nor should it be considered, an admission that such prior art was widely known or forms part of the common general knowledge in Australia, or in any other jurisdiction, before the priority date of any of the appended claims.

According to a first aspect of the present invention, there is provided an electronic seal comprising a sealing mechanism that seals a value item, a transponder receptacle, and an actuator for a transponder held in the transponder receptacle that is actuated upon engagement of the sealing mechanism, wherein the electronic seal maintains a transponder held in the transponder receptacle in an inoperable state until and only until the actuator is actuated.

Preferably, the sealing mechanism comprises a receptacle to receive a locking member and wherein insertion of the locking member in the receptacle causes the actuator to actuate.

Preferably, the electronic seal comprises an electrically conductive object and wherein actuation of the actuator results in movement of the electrically conductive object away from a position where it can contact a transponder held in the transponder receptacle.

Preferably, the transponder receptacle comprises at least a portion that is shaped and dimensioned to hold at least one part of at least one antenna of a transponder in a curved shape. The curved shape may have a convex side facing away from the sealing mechanism and a concave side facing towards the sealing mechanism.

Preferably, the transponder receptacle is formed within a cover for the sealing mechanism. The electronic seal may be adapted for use to seal a shipping container having at least one door, wherein the sealing mechanism is adapted to seal the at least one door and the cover maintains the transponder in an orientation outwards of the at least one door.

According to a second aspect of the present invention, there is provided a transponder housing for a transponder having a flexible antenna structure, the housing including a transponder receptacle that extends into three planes so as to enable a transponder located in the transponder receptacle to transmit a signal over a wider range of angles than if the transponder receptacle were planar.

Preferably, the transponder housing forms part of an electronic seal comprising a sealing mechanism that seals a value item, and a cover one of formed integrally with and secured to the sealing mechanism, wherein the cover inhibits access to the sealing mechanism without first either removing the cover from the sealing mechanism or damaging at least one of the cover and any transponder held in the receptacle.

Preferably, the transponder receptacle has a non-linear shape along a first axis and a substantially planar shape along a second axis that is transverse to the first axis. The non-linear shape may be a curve.

Alternatively, the transponder receptacle has a non-linear shape along two orthogonal axes. The non-linear shape may be a curved shape.

Preferably, the housing is attachable to a separate object and is shaped and dimensioned to maintain the transponder in a required orientation after it has been attached to the object.